1. Field of Invention
The present invention relates to the mounting of packaged electronic assemblies to a substrate. More particularly the invention is directed to a spring clip for mounting a heat sink-containing packaged transistor device or other electronic device to a heat sink substrate which removes heat generated by the device.
2. Description of Related Art
As seen in FIG. 1 a conventional spring clip 10 is of an inverted U-shape configuration and includes a central inwardly-bent bight portion 11 overlying a transistor device package 18, with bent tip ends 12, 14 which by a bi-directional motion, vertical and horizontal, is inserted into a heat sink panel 15. The tip ends 12, 14 are spring pressed into respective oval apertures 16, 17 in panel 15 so that the bent bight portion forces the device package 18 against the heat sink panel. The tip bent ends of adjacent clips, e.g. end 12, may share a common panel aperture 16 with an adjacent clip or both clip tip bent ends, e.g. ends 12, 14, may be clipped into separate panel apertures 16, 17. A separate clip 10 is needed for each package 18 and at least four panel apertures are necessary to mount three linearly-aligned packages. Such apertures, as is apparent, lessen the heat rejection area of the heat sink panel. Likewise, only a very small contact area at the central bend 11 is in contact with the top of the package and since the clip 10 is relatively narrow in width i.e. about 3 mm, only a very small heat conduction path is provided from the typical 8 mm wide package top. This results in a limited clip area provided for radiation of whatever little heat is conducted from the package to the clip. Terminal leads 19 typically extend from a side wall of the device package.